Device for illuminating organic objects

ABSTRACT

The invention relates to a device for illuminating organic objects, particular organic objects of the eye. Preferably, the device can be used in an opthalmological diagnosis or therapy device. According to the invention, an array of miniaturized light sources is arranged in a spatially defined manner on a plane or a curved surface such that the light sources achieve a packing density that is as high as possible and can be electronically controlled individually in a very quick manner. The light source array is imaged onto the biological object by means of an optical system.

FIELD OF THE INVENTION

The invention concerns a device for lighting organic objects, inparticular the eye. It is preferred for application in ophthalmologicdiagnostic or therapy equipment.

BACKGROUND OF THE INVENTION

In eye medicine, both during diagnosis and therapy, light is frequentlyused. This can be particularly provided, since the eye is mostlytransparent and can be reached by rays of light, practically in itsentirety. Hereinafter, light must be understood as the entire visiblespectrum from ultraviolet to infrared emissions.

Slit lamps, eye-fundus cameras and laser scan ophthalmoscopes areparticularly well known diagnostic devices which work with light.

A slit lamp produces a variable light section by means of a gap pictureprojection in the eye, with which conclusions may be obtained dependingon the condition of the individual media of the eye. Usually the slitimages are produced mechanically by means of the width and length of thevariable gap. From patent DE 101 51 314, whose entire contents isincorporated by reference, a well-known light section may also beproduced by means of an appropriate light distribution from DMDs(digital Mirror devices), LED (Light Emitting Diode), LCD (LiquidCrystal display) or OLEDs (Organic Light Emitting Diodes) for developedmicro displays. What all of these light sources have in common is thatthey permit only a relatively small image frequency, since they showeither mechanically moved parts (DMD) or long image retention.

With a fundus camera, such as the one known from patent DE 298 08 351U1, the eye background is illuminated with a classical light source likea halogen or a mercury vapor lamp and afterwards a photographic ordigital image of the retina is produced. It is also widely understoodthat these photographs can only be taken in certain spectral areas, inorder to cause fluorescence of molecules in interest, which is producedby means of appropriate lighting. For special purposes, flashphotographs are also taken in order to recognize quickly occurringprocesses. However additional photo flash lamps are necessary, whichmust be linked over the appropriate additional optics into the path ofrays. Also, these flash lamps have a limited field rate.

With a laser Scan ophthalmoscope, such as the one described in patent DE198 35 967 C2, the inside of the eye is scanned by means of a 2 or 3dimensional mechanical scanner with positioned laser beam and arisingfluorescence is detected. Because of the mechanical movement of thescanners, the picture recording frequency is limited in this case, sothat rapid procedures cannot be pursued, in addition to whichgeometrical disturbances are produced in the contents of the resultingpicture due to the involuntary movements of the eye. Light-based therapydevices are likewise well known in eye medicine. Thus, treatment ofvisual defects by means of laser radiation removing material from thecornea may be done with equipment such as the one described in patent WO01/66029, whose complete contents are incorporated by reference. Thebeam of a treatment laser is guided by means of a mechanical scannerwhich has moving mirrors, purposefully placed across the treatment area.The mechanics of the scanner are also here the limiting factor forincreasing the treatment speed and thus to reduce the treatment time.

The involuntary eye movements, which arise during treatment, lead todeviations between the intended and the actual place of the materialremoval. The resulting errors can be avoided by using an eye tracker,which detects the momentary position/line of sight of the eye, so thatit can recognize these movements. These movements are then taken intoaccount during the control of material removal and thus balanced.

In U.S. Pat. No. 6,179,422, whose entire contents are incorporated byreference, such an eye tracker is described, which for its part leads anIR laser beam quickly across the pupil of the eye and the eye limbus bymeans of such a scanner. The reflected radiation is detected by means ofa fast photodiode and the movement of the eye can be determined from thecontrast shifts of the pupil flanks and the eye limbus betweenindividual scans. This solution is also limited by the accuracy andspeed of the mechanical scanner.

The invention is also applicable in other procedures for theinvestigation of biological objects such as confocal microscopy, forexample.

From patent EP 485803 B1, all contents of which are incorporated byreference, a con-focal microscope is well known, which uses a LED or aLCD array for lighting the sample and analyzes the lighted sample bymeans of a detector array. Therefore, this microscope is not suitablefor the examination of quick procedures. Also, for example, laserscanning microscopes, known from patent DE 197 33 195 A1, use mechanicalscanners to deflect laser beams used for lighting the sample and are,therefore, likewise not suitable for the investigation of very fastprocedures. However, only in recent years the interest in theinvestigation of extremely fast molecular reciprocal effects in biologyhas substantially risen.

SUMMARY OF THE INVENTION

The purpose of the invention is to circumvent the disadvantages of thestate of the art and to provide an extremely fast variable lighting.

According to invention, an array of miniaturized light sources isarranged on a planar or a curved surface in such a spatially defined waythat these light sources achieve a component density as high as possibleand may be individually controlled electronically in a very fast way.Thereby the individual light sources array can form a regular andclosely packed rectangle, as well as an arbitrary one, so that differentadapted evaluation forms can take place.

This light source array can be represented by means of an optical systemon the biological object.

In case of a diagnostic device or a microscope, the device according toinvention includes a detector, which registers and supplies thereflected, scattered or fluorescent radiation portions of the diagnosticobject to an evaluation unit, whereby this detector can also detectselected wavelengths, if necessary. The advantage of the invention isthat a spatially highly resolved structured lighting can be achievedwithout any moving parts, very fast and with variable spectra. The eyeposition can be determined with an eye tracker by fast individualdetectors, where the spatial dissolution is already given by the mappedlight source array, so the use of image-processing CCD sensors is notnecessary.

If the resolution given by the spatial arrangement of the light sourcesis not sufficient, according to invention this can be adapted in thedevice by a making a smaller mapping on the object. In a diagnosticdevice, it is convenient to calibrate the lighting device, for exampleover a homogeneous object. In a therapy device, the benefit is that thedelivered beam is homogenized by means of homogenizing intermediateoptics (for example, based on micro-optical elements).

With the possibility of selecting the spatially structured intensity andcolor/wavelength of the individual light sources, temporarily andspectrally variable intensity profiles can be generated, which can beadapted to different application purposes. It is advantageous, if thelighting device consists of a miniaturized light source array formed bycompact light-emitting semiconductor diodes or semiconductor lasers thatshow an emission divergence as small as possible and has very fastswitching times, whose emission intensity is electronically adjustable.A particularly suitable design for the light sources is the VerticalCavity Surface Emitting Laser (VCSEL), which is described in the book ofK. J. Ebeling “Integrated Optoelectronics”, Springer Publishers, Berlin1992. For example, in patent EP 905 835 A1, a two-dimensional array ofVCSEL light sources is described, which are individually addressable orcontrollable. In U.S. Pat. No. 6,174,749 a manufacturing process forproducing different wavelengths/colors out of radiating VCSELs isdepicted in the book of Connie J. Chag-Hasnain, “Tunable VCSEL”, IEEE J.Selected Topics in Quantum Electronics, Volume 6 (2000) No. 6, P. 978 FFwhich also describes tunable VCSELs.

In order to increase the object lighting homogeneity or structure, theemission profiles of the individual beam sources can be accordinglyselected, in order to obtain an intensity profile in the projectedoverlapping as homogeneous or structured as possible. Gauss-shapedintensity profiles are favorable for homogeneous illumination. Anincrease of the dissolving power of the device according to inventioncan be accomplished by a time or intensity dependant modulation ofparticular and/or neighboring light sources of the light sources array.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in further detail in the following schematicdesigns.

FIG. 1 shows the basic principle of the invention.

FIG. 2 shows the application of the invention as an ultra fast scanner.

FIG. 3 shows multi-spectral lighting.

FIG. 4 shows the application form of a co-focal detector.

FIG. 5 shows the application form of a refractor.

FIG. 6 shows the application form of a perimeter.

FIG. 7 shows the application form of a fluorescent camera.

DETAILED DESCRIPTION

In FIG. 1, an array 1 formed by individual light sources 2, which forexample can be VCSEL elements arranged in such a way that biologicalsample 4 is mapped over projection optics 3.

The individual light sources 2 of array 1 can be controlled by means ofa computer 5, which can regulate their intensity, color (wavelength)and/or illumination period. The control circuit required for thispurpose is not represented here. The outgoing light reflected,scattered, or otherwise emitted from a fluorescent source of the samplewill be mapped by means of mapping optics 6 on a detector 7, which isconnected to computer 5. The evaluation of the information received fromdetector 7 can take place then in computer 5 according to the broadlyknown and intended targeted application adapted procedures.

FIG. 2 shows a series of light sources 2 on array 1 that will besuccessively switched on and off under control of computer 5, in ultrashort time intervals (ranging from a few ns to μs). Using the projectionon sample 4, the scanning will take place very fast depending on thesample and will be accomplished without mechanical elements. The lightradiated from sample 4 is received by detector 7 and analyzed incomputer 5. Such a configuration form can be applied for example as aneye tracker, a digital slit lamp, in the pupilometry or as a scanningfundus camera. Likewise, a laser-scanning microscope can be assembledaccording to this basic structure. FIG. 3 depicts an application inwhich the individual light sources 2, 2′, 2″ of array 1 radiatedifferent wavelengths. In this way, that allows them to detect thewavelength profile of sample 4, as it is used for example in scanningfundus cameras. FIG. 4 shows the application of a device according toinvention in con-focal microscopy, in which the scanned laser beam fromthe light source array and the con-focal detector is replaced by a microlens array with a coupled receiving chip, a CCD chip (similar to aShack-Hartmann sensor). The radiation emitted from the x-y-VCSEL array 1is projected by a 50% dividing mirror (beam splitter cube 8) over theprojection optics 3 into the image plane on retina 9 of eye 10. Thesecondary light sources raster developing there is projected again overthe dividing mirror (beam splitter cube 8) on a sensor array 11, forexample with a micro lens 12 and electronic evaluation. The sensor arraywill assume the function of the conventional detector with an aperturein a multiple array configuration. A first configuration form of sensorarray 1 can be the spatial structure of the adapted micro lens array ofthe VCSEL array coupled with a CCD chip. Each individual miniature lensof the micro lens array takes over the function of mapping optics 6. Theshutter function of the conventional detector with aperture is carriedout, for example, by the fact that the reflected intensity can only beevaluated centrically in each case by the upstream micro lens pixelslying on sensor array 11, which the others do not detect. However, theoff center pixels in each case can be used around the grid given by thestructure of the device to smooth according to invention. The secondconfiguration form can also use an aperture mask and associatedindividual receiving diodes, whereby here again the structure and gridto be considered are those from light source array 1.

Each of these configurations can be used also in connection with amicroscope for the investigation of biological preparations. Inaddition, wave front sensor can also be made according to Hartmann-Shackwith this configuration and the appropriate evaluation algorithms.

This new con-focal scanning microscope can be implemented in a verycompact and durable design without moving parts and can, hence, beapplied in a trial application in an eye with lower expenses. Therefore,the scanning function can be explained by the fact that the successivelyneighboring VCSEL's are switched on and off and thus temporally scannedaccording to the conventional principle. However, this emulation is notnecessary if sensor array 11 possesses an accordingly high evaluationcapacity, as the light sources 2 are switched on at the same time andthe received signals are evaluated at the same time. The cyclic durationof the optimal reception intensity can be adjusted. Further, extremelyfast dynamic procedures can also be examined by the pulsating operationmode of the system.

FIG. 5 depicts the application of the device according to invention in arefractor, whereby the optical structure corresponds to a large extentto the one shown in FIG. 4. The radiation emitted by the x-y-VCSEL array1 is projected for example by a 50% dividing mirror (beam splitter cube8) over projection optics 3 on the retina 9 of eye 10. The raster of thesecondary light sources developing there is projected again over thedividing mirror (beam splitter cube 8) on a sensor array 11, forexample, with micro lenses 12 and the electronic evaluation.Schematically the eyepiece is formed by a normal sighted (emmetropic)eye (reference symbol 13), and are also represented for an eye withdefective vision (ametropic) (reference symbol 14). A ray of light 16emitted from VCSEL array 1 gets to different locations on Retina 9through the different openings in eye-part 13 and/or 14. The reflectionat retina 9 leads in the case of the normal sighted eye to the reflectedray 16, which is directed by the dividing mirror of the dividing cube 8on sensor element 18 of sensor array 11. For the eye with defectivevision, there follows reflection into ray 17, which meets another sensorelement, sensor element 19. Thereby the mapping behavior of eye 10 canbe determined from the different places impacted by the reflected ray atsensor array 11, which is detected electronically and conveyed tocomputer 5.

FIG. 6 shows a device according to the invention to determine the visualfield of a patient.

The radiation emitted from the x-y-VCSEL array 1 is projected overprojection optics 3 on Retina 9 of an eye 10, whereby rays S1, S2, S3 ofdifferent elements from the VCSEL array 1 strike different locations R1,R2, R3 of retina 9. An additionally existing target 20, which forinstance can be a yellow LED or a specific sample represented by theVCSEL array 1, serves for the eye adjustment. The sensory impressioncaused by the impact of rays S1, S2, S3 over the Retina can then bedetermined subjectively in a well-known way, either by the interactionof the patient or objectively by evaluating the nerve impulses to thebrain stream. Appropriate configurations and evaluation procedures areindicated for example in patent documents DE 198 55 848, DE 199 61 323,DE 101 40 871 and DE 101 46 330, whose entire contents is incorporatedby reference.

FIG. 7 shows a device according to the invention in a fluorescentcamera. The radiation emitted from the x-y-VCSEL-array 1 with a certainexcitation wavelength λ₁ is projected for instance by a 50% dividingmirror (beam splitter cube 8) over projection optics 3 on the retina 9of an eye 10 and the tissue found there is stimulated by means of aninserted fluorescent dye with a fluorescence wavelength λ₂. Thefluorescent light that arrives over the beam splitter 8 to the receiver11 is coupled with computer 5. In order to prevent the stimulating lightfrom reaching the receiver, a band elimination filter 21 is connectedupstream for wavelength λ₁. For example, the tissue characteristics canbe detected reliably by evaluating the local distribution of thefluorescent light. If the VCSEL array 1 according with the applicationexample shown in FIG. 2 can emit several wavelengths, it can alsostimulate and detect the different corresponding fluorescences. Thecornea or the eyepiece can be spectrally examined in the same way withthe device according to invention.

Therefore, each light source can be assigned a directly neighboringdetector for monitoring the intensity and/or color, as is described inpatent EP 829 933 A2.

In the context of this representation and the device according toinvention, all diode lasers can be understood by the concept of a VCSELlight source, whose radiation direction lies perpendicularly to thesurface of the array or their active zone. It can thereby concern, inparticular, also around NECSEL (Novalux extended cavity surface emittinglasers) or diode lasers, whose resonator lies essentially parallel tothe active zone, and are provided with a bending or reflectingstructure, which uncouples laser radiation perpendicularly from thearray or from the active zone.

The present invention may be embodied in other specific forms withoutdeparting from the spirit of the essential attributes thereof;therefore, the illustrated embodiments should be considered in allrespects as illustrative and not restrictive, reference being made tothe appended claims rather than to the foregoing description to indicatethe scope of the invention.

1. A device for illuminating organic objects, comprising: a controllablelight source; and mapping optics, in which the controllable light sourcecomprises a plurality of individual light sources, whose intensityand/or color can be changed with a frequency greater than about 100cycles per second.
 2. A device for lighting organic objects according toclaim 1, in which the frequency is greater than about 1000 cycles persecond.
 3. A device for lighting organic objects according to claim 1,in which the frequency is greater than about 10,000 cycles per second.4. A device for lighting organic objects according to claim 1, in whichthe frequency is greater than about 100,000 cycles per second.
 5. Adevice for lighting organic objects according to claim 1, in which thefrequency is greater than about 1,000,000 cycles per second.
 6. A devicefor lighting organic objects according to claim 1, in which thefrequency is greater than about 10,000,000 cycles per second.
 7. Adevice for lighting organic objects according to claim 1, in which theindividual light sources are arranged in a regular one or twodimensional array.
 8. A device for lighting organic objects according toclaim 1, in which the individual light sources are arranged in asubstantially planar array.
 9. A device for lighting organic objectsaccording to claim 1, in which the individual light sources are arrangedin a curved array.
 10. A device for lighting organic objects accordingto claim 1, in which light returned from the organic object is receivedby at least one detector.
 11. A device for lighting organic objectsaccording to claim 10, in which the light received by the detector isanalyzed spatially, temporally and/or spectrally.
 12. A device forlighting organic objects according to claim 10, in which the individuallight sources comprise light-emitting semiconductor diodes orsemiconductor lasers, whose intensity and/or color are controllableelectronically.
 13. A device for lighting organic objects according toclaim 10, in which the light sources are arranged before one or moremicro-optical elements.
 14. A device for lighting organic objectsaccording to claim 10, in which at least one of the light sourcesfurther comprises a detector for monitoring the intensity and/or colorof the light source.
 15. An opthalmologic diagnostic unit, comprising atleast one device for lighting organic objects according to claim
 1. 16.Opthalmologic therapy equipment comprising at least one device forlighting organic objects according to claim
 1. 17. A confocal microscopecomprising at least one device for lighting organic objects according toclaim
 1. 18. A slit lamp, comprising at least one device for lightingorganic objects according to claim
 1. 19. A fundus camera, comprising atleast one device for lighting organic objects according to claim
 1. 20.A laser opthalmoscope, comprising at least one device for lightingorganic objects according to claim
 1. 21. An eye tracker, comprising atleast one device for lighting organic objects according to claim
 1. 22.Wave front sensor, comprising at least one device for lighting organicobjects according to claim
 1. 23. A Shack-Hartmann type wave frontsensor, comprising at least one device for lighting organic objectsaccording to claim
 1. 24. A refractometer, comprising at least onedevice for lighting organic objects according to claim
 1. 25. Aperimeter, comprising at least one device for lighting organic objectsaccording to claim 1.